Scrap metal. An honest person collects it from properties that are being cleaned up, from industrial places (ie old water heaters, plumbing fittings, car wreckers) also abandoned properties (maybe for a real estate) and the tip if you have scavenger rights. I guess you could find old cars and other items in the bush.
A dishonest person might use it as a cover to enter people's properties and scope the place (this has happened where I work and to several other properties locally).
A dishonest person could also 'steal' scrap metal. Many items are popular including industrial water meters, new houses that are not finished have had all their pipework stolen. Plaques are a popular item to get stolen too. Plaques in graveyards perhaps??